//Accepted
#include <cstdio>

int main(){
	int l, d, v, g, r, x;
	scanf("%d %d %d %d %d", &l, &d, &v, &g, &r);
	x=((d/v)%(g+r));
	if(x<g) printf("%.8lf", ((double)l)/v);
	else printf("%.8lf", d/v + (g+r-x) + ((double)(l-d))/v);
	return 0;
}
